For convenience purposes, it is well known to provide garage doors which utilize a motor to provide opening and closing movements of the door. Motors may also be coupled with other types of movable barriers such as gates, windows, retractable overhangs and the like. An operator is employed to control the motor and related functions with respect to the door. The operator receives command signals for the purpose of opening and closing the door from a wireless remote, from a wired or wireless wall station or other similar device. It is also known to provide safety devices that are connected to the operator for the purpose of detecting an obstruction so that the operator may then take corrective action with the motor to avoid entrapment of the obstruction.
How safety devices are used with a door operator system have evolved from the days of no uniform standard to the currently applied government regulations as embodied in Underwriters Laboratories Standard 325. UL Standard 325 encompasses safety standards for a variety of movable barriers such as gates, draperies, louvers, windows and doors. The standard specifically covers vehicular gate or door operators intended for use with garages and/or parking areas. Such devices require a primary safety system and a secondary safety system which are independent of each other. Primary entrapment systems sense the operator motor's current draw, or motor speed and take the appropriate corrective action if the monitored value is exceeded. Primary systems must be internal within the operator head. Secondary entrapment systems are typically external from the operator head and may include a non-contact or contact type sensor. But, secondary systems may also be internal to the operator head as long as they are independent of the primary system.
One of the more widely used non-contact safety devices is a photo-electric eye which projects a light beam across the door's travel path. If the light beam is interrupted during closure of the door, the operator stops and reverses the travel of the door. Contact type safety devices such as an edge-sensitive pressure switch, which is attached to the bottom edge of the door and runs the complete width of the door, may also be used. Other contact safety devices directly monitor the operating characteristics of the driving motor to determine whether an obstruction is present. Typically, shaft speed of the motor is monitored by projecting an infrared light through an interrupter wheel. Alternatively, Hall effect switches or tachometers can be used to monitor shaft speed. Or, the motor Current can be monitored such that when an excessive amount of current is drawn by the motor—which indicates that the motor is working harder than normal—it is presumed that an obstruction has been encountered. It is also known to monitor door speed with a sliding potentiometer, wherein a rate of change is equated to the speed of the door and wherein unexpected slowing of the door triggers corrective action by the operator. The secondary entrapment requirement may also be met by providing an operator that is capable of receiving continuous pressure on an actuating device that is in the line of sight of the door and maintains the opening or closing motion until the respective limit position is reached. Regardless of how the safety devices work, their purpose is to ensure that individuals, especially children, are not entrapped by a closing door. Opening forces of the door are also monitored to preclude damage to the operating system for instances where an object or individual is caught upon a door panel as the door moves upwardly.
Safety devices perform their function within the operator's direction control logic sequence where each operational signal sent to the motor controls initiates a different movement of the barrier. For example, if a barrier door is fully-closed, the next user command causes the door to open. If the barrier is fully open, the next user command causes the barrier to close. If the barrier is stopped, partially open, that is, between the fully-open and the fully-closed, then the barrier operator typically uses one of the following controlling logic sequences:                a) Four-Phase Logic: The barrier's next direction is opposite of its last direction. If the barrier's last direction was opening, then the next direction will be closing. If the barrier's last direction was closing, the barrier's next direction will be opening.        
That is, each user command to the barrier operator steps the barrier's movement through four-phases: Open-Stop-Close-Stop-Open- . . . .                b) Open Only Logic: A stopped, partially open barrier can only be commanded to open. Only when the barrier is fully open, can a user command the barrier to close.        
Although the operational logic remains the same, there are also motors that have separate directional windings where the first winding moves the door in the first direction and a second winding moves the door in the opposite direction. One exemplary device is shown in U.S. Pat. No. 5,841,253 to Fitzgibbon, et al. The '253 patent discloses a garage door opening and closing apparatus having improved operational safety features. The apparatus includes a control circuit which responds to a number of input stimuli to generate commands to open and close a garage door as well as to stop garage door movement. Three relays respond to the commands via drive circuitry to actually connect door operating voltages to the windings of a door controlling motor. By redundancies in the operation of the three relays, faults in the operation of those relays result in safe door operating conditions. Additionally, the control circuitry upon issuing a door stop command performs a test to determine whether or not the door is still moving. If the door is still moving, door up commands are generated by the control circuitry to place the door in a safe position.
In the prior art, garage door operators can create un-anticipated hazards using “four phase logic” and can be less of a hazard but a nuisance using “open only logic.” To give an example, if a user partially opens their garage door from the fully closed position to a height to allow venting of the garage or egress of a pet and the pet becomes lodged or wedged in the opening, then the user's first reaction may be to activate the door to open freeing the trapped animal. If the operator has “four phase logic,” the next movement of the door would be in the closing direction increasing the force on the trapped animal. If the operator used “open only logic,” the door would go up to its fully open position and the animal would be freed. However, stopped partially opened doors controlled by operators with “open only logic” will always go up when activated and must reach the upper travel limit before it can go down again. Therefore in the evening when the user wants to close the door, the door must travel to its upper limit, stop, and receive another signal to send it to the closed position.
Garage door operators should undergo a monthly obstruction reversal test where the door is closed on a 2″ by 4″ block of wood and the door must reverse when it hits the obstruction. If the door doesn't reverse, the user is required to reduce the down force by making an adjustment and continue to test and adjust until the door reverses. With an “open only logic,” the door always returns to the full open position before another adjustment is made. Accordingly, making the adjustment for obstruction detection of operators with this type of control logic time is quite time consuming. This is normally considered to be an unacceptable nuisance. Further, if the number of door opening and closing cycles necessary to establish the force settings is excessive, the motor will heat up and the motor's thermal protector will open. This action shuts the motor down for a period of time preventing further settings until the motor cools down which also results in an unacceptable nuisance.
Normally, as the door is traveling in a downward direction and the door movement is blocked by an obstruction, the door will stop and reverse to the fully open position. During the reversal period, it is common to restrict further door movement commands for a period of time or distance to ensure the door will properly be removed off the object that caused the reversal. Indeed, typical residential garage door operators, upon detecting an obstruction of a downward moving door, stop the door's travel, pause for a short time (0.1 s to 1.0 s typical), and then the door begins upward travel to the full-open position. During this stop-pause-upward sequence, a user may command the door using a remote control or a wired control. A user door command during the stop-pause-upward sequence could stop the door completely, not allowing the sequence to complete. Such a device is disclosed in U.S. Pat. No. 6,239,569. And published patent application U.S. 2003/0154656 A1, discloses a system which inhibits user commands during the stop-pause-upward sequence.
Another system is described in U.S. Pat. No. 4,338,553 to Scott, Jr. which discloses a system that controls a motor which drives an operating mechanism for moving a barrier, such as an overhead garage door, in either direction between a closed position and an open position in response to actuation of a start switch. The control system includes an encoder including a rotatable disc driven by the motor, and control circuitry including an encoder pulse verification circuit associated with the encoder for detecting the direction of door movement as well as increments of travel by the door when the door is moved by the motor under control of a motor command circuit in response to actuation of the start switch. The start switch and a start circuit cooperate with the motor command circuit for energizing the motor to move the door in one direction, for de-energizing the motor to stop the door at any position, and for re-energizing the motor to reverse the door in response to repeated actuation of the start switch. An up/down counter circuit is responsive to the direction as well as the increments of travel by the door for containing a count representative of the actual position of the door. A programming circuit is included for setting an up limit set point which is stored in a latch circuit. A decoder circuit cooperates with the motor command circuit, the up/down counter circuit, the latch circuit, and a comparator circuit for de-energizing the motor when the door reaches the up limit set point as the door is opened. The decoder circuit cooperates with the motor command circuit and the up/down counter circuit for de-energizing the motor when the door reaches the threshold as the door is closed. An obstruction detector circuit is responsive to rate of movement of the door for sensing an obstruction. The obstruction detector circuit cooperates with the motor command circuit for de-energizing the motor if an obstruction is sensed as the door is opened and cooperates with the motor command circuit, the up/down counter circuit, and the decoder circuit for reversing the motor if an obstruction is sensed as the door is closed unless the door is a predetermined distance or less above the threshold whereupon reversal of the motor is inhibited and the motor is merely de-energized. A reset circuit is included for resetting the control circuitry so that the initial actuation of the start switch will cause the door to be opened. This type of system uses the basic close/stop/open/stop sequence logic for motor response to push button input, either from a hardwired switch or radio frequency remote.
U.S. Pat. No. 5,191,268 to Duhame discloses an automatic door operator with a continuously monitored supplemental obstruction detector. In a first embodiment, the obstruction detector is a radiant beam obstruction detector that transmits a beam of modulated radiant energy across the door opening. A safety signal generator produces an active safety signal only on unobstructed receipt of radiant energy by a receiver. Failure to receive the active safety signal when the motor is closing the door at least stops the door. A two-wire cable, which carries both power and the active safety signal, connects the supplemental obstruction detector to the automatic door operator. Constant activation of a portable transmitter or of a local push button can override the supplemental obstruction detector to close the door. An alternative supplemental obstruction detector includes a safety edge having a compressible tube disposed on a leading end of the door. Plural conductors change their conductive state upon compression of the compressible tube. This embodiment may include a delay upon detection of compression of the compressible tube so that contact with the floor is not detected as an obstruction. This type of controller includes a provision to override the obstruction signal to close the door. Constant activation of the portable transmitter or constant depression of the local push button overrides the obstruction detector. In an alternative embodiment, only constant depression of the local push button will override the obstruction detector permitting closure of the door.
U.S. Pat. No. 5,278,480 to Murray discloses a garage door operator with a microcomputer based control which is programmed to measure door position from full open position by counting motor revolutions and to determine motor speed and deceleration for each revolution. The program learns the open and closed position limits as well as force sensitivity limits for up and down operation with minimal user input. During normal door operation the closed limit and the sensitivity limits are adaptively adjusted to accommodate changes in conditions. The lowest up and down motor speeds in each operation are stored for comparison with motor speeds in the next like operation for obstruction detection. Motor deceleration is also monitored for obstruction detection. For more sensitive obstruction detection during closing, the motor speed is mapped for each revolution for the last several inches of closing. The map is stored after each successful closing operation and the corresponding speeds in the next closing are compared point-by point with the mapped speeds to detect slow down due to touching an obstruction. To make the door operator more responsive to an obstruction during its lower range in closing direction than is possible by the single value closing sensitivity limit, the motor speed is mapped at each motor revolution during each closing over the final several inches of travel, say, from 12 inches above the closed position limit to the obstruction reference, and the mapped values are stored in the controller. Then, during the next closing operation each newly measured motor speed is compared to the stored speed at the corresponding door position. If the motor speed is below the stored value by a predetermined offset, an obstruction is detected and the door will be caused to stop and then reopen. Whenever the door closes without detection of an obstruction, the most recent set of mapped speeds is substituted for the previous one. Although this method causes the door to “stop and then reopen” there is no provision to allow the door to stop in response to the next command and continue to open on the subsequent command.
U.S. Pat. No. 5,285,136 to Duhame discloses an automatic door operator with a continuously monitored supplemental obstruction detector much like the one disclosed in Duhame's '268 patent. This disclosure is distinguishable in that it includes an oscillator sealed within the tube at one end which supplies the safety signal. This embodiment may include a delay upon detection of compression of the compressible tube so that contact with the floor is not detected as an obstruction.
U.S. Pat. No. 5,428,923 to Waggamon discloses that a light beam utilized in an obstruction detector is coded into packets of pulses by a transmitter according to a code generated only by the transmitter. When the light beam is received, the receiver recovers the code signal and supplies it to a code detection circuit. In one preferred embodiment, to detect the code, the code detection circuit supplies the code signal and a delayed version of the code signal to an “exclusive or” gate. In another embodiment, a frequency detection circuit determines whether the code signal detected by the receiver is within a predetermined permissible range. If the code is not present, the door operator system reverses the door if it is closing, and prevents the door from closing if it already is in the up position, or if it is opening. The door operator system will operate in this way not only in response to obstructions, but also, in response to errors and malfunctions in the wiring to the transmitter and receiver, and in the transmitter and receiver themselves.
In summary, the prior art either accepts and handles the user's barrier command as a normal command to start or stop the barrier; uses the command sequence to open/stop/close/stop the barrier; or, in the event of an obstruction detection, the user commands are locked out for a period of time while the door stops, reverses, stops or returns to its fully open position. As noted, some prior art prevents the user from entering a door command for a period of time after an obstruction event or until the barrier has traveled a predetermined distance. In either case, the user, who may be in an excited condition at the occurrence of an entrapment, may repeatedly actuate the control buttons which may result in the barrier moving downwardly and causing further injury. Therefore, there is a need in the art for corrective action to be taken by the operator upon detection of an obstruction, but wherein the correction action still allows the user to have at least limited control of barrier movement.